Method of repairing cracks in metal castings



Feb. 5, 1935. c. A. JENSEN METHOD OF REPAIRING CRACKS IN METAL CASTINGS Filed July 29, 1933 raaaaa res. -e.,ieas

PATENT OFFICE METHOD OF REPAIRING CRACKS IN METAL CASTINGS Charles A. Jensen, Los Angeles, Calif., assignor of one-half to Grace E. Jensen Application July 29, 1933, Serial No. 682,892

10 Claims.

My invention relates to a method of repairing cracks in castings of hard brittle metal and has for its principal object, the provision of a relatively simple and easily practiced method whereby cracks in cast metal structures and particularly those structures that are subjected to a wide range of temperature changes may be easily and economically repaired so as to efiectually prevent leakage of fluid pressure through the crack and to hold the edges of the metal immediately adjacent to the crack, rigidly in position so as to prevent any appreciable movement of said edges relative to each other during temperature changes and which movement would otherwise tend to disturb the material used for sealing the crack and thereby reopen the same.

Under the present practice cracks in hard brittle metal castings such as engine cylinder blocks, are difficult to repair, for if the cracks are welded, there is nothing to prevent temperature changes from developing strains in the metal immediately adjacent to the crack and which strains tend to disturb the welding metal and reopen the crack especially if the crack does not run out to the edge of the casting.

I have discovered that by drilling holes in the crack and inserting tapered pins or wedges and then calking or sealing the crack between the pins or wedges, the crack may be completely sealed and the strains and stresses in the metal adjacent to the crack relieved and eliminated.

In internal combustion motors warping and the development of cracks is brought about as a result of temperature changes. Therefore the edges of a crack will be disturbed whenever the motor is started or stopped.

Under such conditions the movement of the metal adjacent to the crack as the same opens and closes, tends to disturb and break or loosen the cement or calking that is applied to the crack.

By the use of tapered pins or wedges in the repair of cracks in cast metal and particularly in engine cylinder blocks, the cooling effect of the water circulating through the block is transferred through the inserted pins or wedges to the metal in the block immediately adjacent to the crack, thereby tending to maintain normal cooling conditions.

In the water jackets of water cooled structures and particularly engine cylinder blocks, a layer of scale forms on the inner surfaces of the walls and this layer of scale is much thicker on the parts that are subjected to the greatest heat. As this condition is undesirable I propose to drill holes through the walls of the casting and the scale thereon and insert tapered pins or wedge plugs in said holes and if these pins or plugs may be readily withdrawn and renewed on account of their taper, said plugs may be readily withdrawn and replaced when scale forms thereon so as to insure the highest eiiects of the circulating cooling medium within the water jacket.

In practicing my improved method the outer portion of the crack is calked or filled with a suitable sealing medium either metal or cement and under such conditions I find that the inner portions of the crack will in a short time become filled with scale that develops within the water jacket and thus the cementing or sealing of the crack is accomplished both mechanically by the cement or calking placed in the outer portion of the crack and chemically by the scale that fills the inner portions of the crack.

In the accompanying drawing:

Fig. 1 is a plan view of the upper surface of an engine cylinder block having a crack extending between the piston chamber and one of the inlet or exhaust ports.

Fig. 2 is a plan view similar to Fig. l and showing a plurality of tapered pins or plugs driven into the holes that are drilled in the cylinder block along the crack therein.

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 2.

Fig. 4 is a vertical section similar to Fig. 3 and showing theupper portions of the pins cut off flush with the top of the cylinder block and with calking or sealing material positioned in the upper portion of the crack.

Fig. 5 is an elevational view of a tapered pin that may be utilized in practicing my improved method.

Fig. 6 is a perspective view of a modified form of a crack repairing pin and which is slotted 1ongitudinally for the reception of wedges.

Fig. 7 is a perspective view showing the wedges that are utilized with the form of pin illustrated in Fig. 6.

Fig. 8 is a perspective view showing a series of repair pins disposed. adjacent to each other and slotted for the reception of a single elongated wedge.

Fig. 9 is a detail section of a portion of a cast metal wall having a crack that has been repaired in accordance with my invention and showing the scale on the inner surface of the wall and in the lower portion of the crack.

Fig. 10 is a detail plan view showing a crack repaired by means of a series of tapered pins or pins or plugs are in direct contact with each other.

Referring by numerals to the accompanying drawing, 10 designates a cast metal structure, for instance, the upper portion of a cylinder block wherein a crack C has developed between the piston chamber and port or opening that is closed by one of the valves.

In accordance with my method a series of holes as shown by, dotted lines 11 are drilled through the metal along the crack and tapered pins or plugs 12 are driven into these holes to such a degree as to slightly open the crack but not to increase the length or depth of the crack.

These plugs provide rigid ties or bridges that connect the edges of the metal on opposite sides of the crack and firmly hold said metal against any movement relative to each other as a result of temperature changes.

After the pins or wedges have been inserted as illustrated in Figs. 2 and 3, the projecting upper ends of the pins or plugs are cut ofi flush with the surface of the metal in which they are seated and a suitable sealing compound, either metal or cement, is now driven or calked into the upper portion of the crack between the inserted pins or plugs.

Thus the pins or plugs provide a rigid bond between those portions of the metal on opposite sides of the crack and the latter is effectually sealed by the calked-in sealing material.

The inserted pins firmly hold the metal on opposite sides of the crack from relative movement due to temperature changes and as a result there will be no disturbance of the sealing material after the same has been properly driven into the crack.

Where the pins or plugs extend into a water jacket they are effective in the transference of cooling temperatures from the circulating cooling medium within the water jacket to the wall or walls of the metal in which they are seated.

After the structure having the repaired crack has been in use a short time scale that forms on the inner faces of the walls of the water jacket will enter the lower portions of the crack that are not filled with the calking or inserted sealing material, thus tending to further seal the crack and combining a chemical seal with the inserted mechanical seal.

In the event that those portions of the plugs that project into the water jacket become coated with scale so as to effect their temperature transference functions, said plugs may be withdrawn and replaced by new plugs by drilling holes in the outer portions of the plugs and then inserting in said holes the threaded shanks of hooks or tools so as to apply outward pulling strains on said plugs to remove same. In Fig. 4 I have shown a hook inserted in one of the pins for the purpose of withdrawing the same.

In Fig. 5 I have shown a plain tapered pin adapted for use in practicing my improved method and in Fig. 6 I have shown a pin or plug 13 provided with longitudinally disposed slots 14 that are adapted to receive wedges or keys such as 15 and 16 in order to give tapered effect to the upper portion of the pin or plug.

One of the slots 14 is made considerably longer than the other for the reception of wedge or key 15 and the shorter one of the slots 14, which is arranged at right angles to the longer slot is adapted to receive the shorter wedge or key 16. In order that wedge or key 16 may be inserted the upper portion of wedge or key 15 is provided with a longitudinally disposed slot 1'7.

In some instances where pins or plugs oi larger diameter are used three slots such as 14 may be formed in the pin or plug and said slots being disposed approximately 60 apart.

In Fig. 8 I have illustrated the upper portions of a series of pins or plugs 18 that may be inserted in holes drilled into the cracked portion of a cast metal structure, said pins or plugs being located immediately adjacent to each other and correspondingly slotted as designated by 19 for the reception of a single wedge or key 20.

In Fig. 9 the upper portion of the repaired crack is shown filled with a suitable sealing compound, either metal or cement, and the lower portion of said crack is shown filled with the scale that forms on the inner face oi. the wall of a water pins extend into the fiuid cooling medium and as they have intimate contact with the'wall in which they are seated, they function as temperature equalizers and said pins or plugs may be placed in overheated spots of an engine structure to reduce internal strains. Further, the pins or plugs may be used where it is impractical to use screw plugs.

In Fig. 10 I have illustrated a crack that is repaired by the insertion of tapered pins or plugs that are driven into holes drilled along the crack and intersecting the same and which pins are in direct contact with each other, thereby eliminating the necessity for the insertion of a sealing compound into the crack.

In the practice of my improved method, it will be understood that the pressure created by driving tapered pins or plugs into prepared apertures and also the driving of wedges into the slotted pins or plugs, braces the material in the repaired structure immediately adjacent to the crack and prevents relative movement thereof and the plugs are held firmly in the holes as a result of friction between the contacting surfaces.

In some instances it may be round desirable to provide round tapered threaded holes in the cracked structure and which receive threaded plugs and which practice is carried out where it is impractical to use smooth plugs.

The bracing of portions of cast metal structures by my improved method may be advantageously employed for the strengthening of unsound portions of cast metal, for instance, porous spots or sand holes or weakened portions that would otherwise tend to develop cracks under varying degrees of temperature changes.

I claim as my invention:

1. The herein described method of repairing cracks in cast metal structures, which consists in boring holes into the structure along the crack so that portions of said holes extend into the metal to the sides of said crack, then driving tapered pins into said holes so as to slightly open the crack and then placing sealing material in said crack.

2. The herein described method of repairing cracks in cast metal structures, which consists in boring holes into the structure along the crack so that portions of said holes extend into the metal to the sides of said crack, then driving tapered pins into said holes so as to slightly open the crack and then calking said crackwith sealing material.

3. The herein described method of repairing cracks in cast metal structures which consists in boring holes in the structure along the crack therein so that opposite portions of said holes extend into the metal to the sides of the crack. approximately equal distances, then driving plugs into said holes so as to slightly open the crack and then placing sealing material in said crack.

4. The herein described method of repairing cracks in cast metal structures, which consists in boring holes in the metal structures along the crack, then inserting plugs in said holes, then expanding portions of said inserted plugs to slightly open the crack and then placing sealing material in said crack.

5. The herein described method of repairing cracks in cast metal structures, which consists in boring holesin the structure along the crack therein, inserting plugs in said holes, then simultaneously expanding said plugs to slightly open the crack and then placing a sealing compound in said crack.

6. A plug to be, used for repairing cracks in cast metal structures, comprising a substantially cylindrical body having a pluralitypf longitudinally disposed slots for the reception of wedges and one of which slots is longer than the other.

7. The herein described method of repairing cracks in cast metal structures which consists in boring holes in the structures along the cracks therein, then inserting tapered pins or plugs into said holes, said holes being located immediately adjacent to each other so that when the pins are inserted, portions of the peripheral faces thereof are in direct contact with each other.

8. The herein described method of repairing cracks in cast metal structures which consists in boring holes in the structure along the crack therein, inserting pins or plugs into said holes and then expanding said pins or plugs to slightly ex pand the crack in the metal and then welding the crack between the inserted pins.

9. The herein described method of repairing cast metal structures having unsound portions, sand holes or porous spots which consists in drilling holes into the unsound portions, sand holes or porous spots, then inserting pins or plugs in said holes and then expanding said pins or plugs so as to compress those portions of unsound metal immediately adjacent to the holes.

10. The herein described method of repairing cast metal structures having unsound portions, sand holes or porous spots, which consists in drilling holes into the unsound portions, sand holes or porous spots and then inserting pins or plugs into said holes so as to slightly expand and thereby compress the portions of unsound metal immediately adjacent to said holes.

CHARLES A. JENSEN. 

